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Introduction

Electrophysiological study and fluoroscopy-

guided radiofrequency (RF) catheter ablation

(RFCA) have become standard modalities for

treatment of paroxysmal supraventricular

tachycardia.1-2 However, there are serious

limitations in fluoroscopy-guided ablation

procedures, including poor resolution of soft tissue,

poor visualization of the site of origin, difficulty in

mapping complex arrhythmias, and exposure of

patients and physicians to relatively high levels of

radiation.3-4 During the last decade, clinical

applications of the 3-dimensional (3D) mapping

system have enabled real-time display of the

ablation catheter in cardiac anatomy and led to an

increased rate of procedure success in difficult

cases.5-6

In this report, we present the successful catheter

ablation of atypical atrial flutter after open heart

surgery, using a 3D mapping system.

Case & Discussion

In February of 2013, a 65-year-old man was

admitted to the Arrhythmia Center of Seoul

National University Hospital for the management

Catheter Ablation of Atypical Atrial Flutter after Cardiac SurgeryUsing a 3-D Mapping System

Myung-Jin Cha, MD, Seil Oh, MD, PhD, FHRSDepartment of Internal Medicine, Seoul National University College of Medicine and Seoul National University Hospital, Seoul, Korea

Myung-Jin Cha Seil Oh

Catheter ablation of atypical atrial flutter after cardiac surgery using a3-D mapping system

ABSTRACTThree-dimensional (3D) mapping systems are useful tools for the diagnosis and treatment of atypical

arrhythmias following open heart surgery. In this case, a patient experienced incessant tachycardia after

aortic valve surgery. Two-dimensional fluoroscopy-guided catheter ablation and intensive antiarrhythmic

pharmacological treatment, in addition to a permanent pacemaker, failed to control the tachycardia. A 3D

mapping system revealed that the mechanism of the tachycardia involved macroreentry around the right

atriotomy scar, and the tachycardia circuit was blocked by 3D-guided catheter ablation.

Key words: ■ arrhythmias ■ catheter ablation ■ 3D mapping systems

Received: March 26, 2013Accepted: March 30, 2013Correspondence: Seil Oh, MD, PhD, FHRS, Professor of Internal MedicineSeoul National University College of Medicine and Seoul NationalUniversity Hospital 101 Daehak-ro, Jongno-gu, Seoul 110-744, KoreaTel: 82-2-2072-2088, Fax: 82-2-762-9662, E-mail: seil@snu.ac.kr

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34 The Official Journal of Korean Heart Rhythm Society

of incessant atrial flutter. His current medical

problems included hypertension and dyslipidemia.

His medical history was significant for aortic

valve-replacement surgery using a mechanical

valve in 2006. He was regularly followed at the

Cardiac Surgery Center and was taking warfarin,

hydrochlorothiazide, and a statin. He had started to

feel intermittent palpitations with chest pain after

surgery, and was diagnosed with atrial flutter at a

regional hospital. RFCA was performed at that

hospital in 2011, but the patient’s symptoms were

not improved because of failed ablation. His

palpitations were sustained despite the use of

antiarrhythmic agents such as beta-blockers or

amiodarone. In addition, he experienced sudden

syncope and was diagnosed with tachycardia-

bradycardia syndrome by Holter monitoring in June

2012. Although his syncope resolved after

implantation of a permanent pacemaker, he

continued experiencing intermittent palpitations

despite an intensive regimen of antiarrhythmic

medications. Consequently, he visited our

Arrhythmia Clinic in January 2013.

At his visit, 12-lead ECG showed a regular

narrow-QRS tachycardia with 2:1 AV conduction

(Figure. 1). The heart rate was 139 bpm; blood

pressure, 109/78 mmHg. Echocardiography

confirmed a well-functioning mechanical aortic

valve with a normal transaortic pressure gradient

and normal cavity size. However, it also showed

global hypokinetics of the left ventricle, with

decreased systolic function and an ejection fraction

(EF) of 43%. Coronary CT angiography showed no

significant stenosis in the coronary arteries.

After the patient provided written informed

consent, he was transferred to the electro-

physiology laboratory while he was experiencing

tachycardia. Tachycardia cycle length was 226 ms.

Entrainment mapping showed that the difference

between the post-pacing interval (PPI) and

tachycardia cycle length was ＜50 ms at the lateral

wall of the tricuspid annulus and ＞80 ms at the

septal wall (Figure. 2). Therefore, we concluded that

the origin of the circuit was the right atrial free

Figure 1. Tachycardia electrocardiogram. Flutter wave morphology does not show a saw-tooth appearance as in typicalatrial flutter.

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wall rather than the cavotricuspid isthmus-

dependent reentry, and we performed electro-

anatomical mapping using the CARTO 3 system

(Biosene Webster, Diamond Bar, Co USA). The

activation map revealed that the tachycardia

circuit was the right atriotomy scar-related

reentry (Figure. 3). Ablation was performed at gaps

in the scar area and at the isthmus between the

scar and the tricuspid annulus using a Thermocool

SF irrigated catheter (Biosene Webster, Diamond

Bar, CA, USA) and RF energy with 20-25 W.

Tachycardia was terminated during ablation, and

bidirectional block was confirmed after ablation.

Conclusion

Intra-atrial reentrant tachycardia related to

Figure 2. Entrainment mapping. Stimulation was delivered at the septal side using an ablation catheter (ABLd, whitearrow in the fluoroscopy image). Postpacing interval is 310 ms, which indicates that the septal wall is a remote site fromthe reentry circuit.

Figure 3. Electroanatomical mapping. Activation mapshows macroreentry at the right atrial free wall. Red dotsindicate ablation sites on gaps in the scar area and theisthmus between the scar and the tricuspid annulus.Tachycardia was terminated during RF energy delivery atthe area marked by the yellow dot.

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36 The Official Journal of Korean Heart Rhythm Society

postoperative scar tissue often develops after open

heart surgery; this tachycardia is difficult to

manage and may result in significant postoperative

morbidity. In this case, the patient had right

atriotomy scar-related atypical atrial flutter, which

was easy to be misdiagnosed as typical atrial

flutter. The structural changes that occur after

open heart surgery can serve as substrates for

arrhythmias. Treatment of these types of

arrhythmias sometimes requires an unconventional

approach. Studies have reported that in patients

with a history of open heart surgery, atypical

arrhythmia can be successfully cured by catheter

ablation.7-8 Catheter ablation procedures guided by

3D-mapping systems may increase the ablation

success rate and improve patient outcomes.

Reference

1. Jackman WM, Wang XZ, Friday KJ, Roman CA, Moulton KP,Beckman KJ, McClelland JH, Twidale N, Hazlitt HA, Prior MI.Catheter ablation of accessory atrioventricular pathways (wolff-parkinson-white syndrome) by radiofrequency current. N Engl JMed. 1991;324:1605-1611.

2. Calkins H, Sousa J, el-Atassi R, Rosenheck S, de Buitleir M, KouWH, Kadish AH, Langberg JJ, Morady F. Diagnosis and cure of thewolff-parkinson-white syndrome or paroxysmal supraventriculartachycardias during a single electrophysiologic test. N Engl JMed. 1991;324:1612-1618.

3. Ben-Haim SA, Osadchy D, Schuster I, Gepstein L, Hayam G,Josephson ME. Nonfluoroscopic, in vivo navigation and mappingtechnology. Nat Med.1996;2:1393-1395.

4. Schumacher B, Jung W, Lewalter T, Wolpert C, Luderitz B.Verification of linear lesions using a noncontact multielectrodearray catheter versus conventional contact mapping techniques. JCardiovasc Electrophysiol.1999;10:791-798.

5. de Groot NM, Bootsma M, van der Velde ET, Schalij MJ. Three-dimensional catheter positioning during radiofrequency ablationin patients: First application of a real-time position managementsystem. J Cardiovasc Electrophysiol. 2000;11:1183-1192.

6. Wittkampf FH, Wever EF, Derksen R, Wilde AA, Ramanna H,Hauer RN, Robles de Medina EO. Localisa: New technique forreal-time 3-dimensional localization of regular intracardiacelectrodes. Circulation. 1999;99:1312-1317.

7. Triedman JK, Saul JP, Weindling SN, Walsh EP. Radiofrequencyablation of intra-atrial reentrant tachycardia after surgicalpalliation of congenital heart disease. Circulation. 1995;91:707-714.

8. Van Hare GF, Lesh MD, Ross BA, Perry JC, Dorostkar PC.Mapping and radiofrequency ablation of intraatrial reentranttachycardia after the Senning or Mustard procedure fortransposition of the great arteries. Am J Cardiol. 1996;77:985-991.

자율학습문제

1. Remote-controlled 시스템중magnetic navigation 시스템에대한설명이아닌것은?

①자기장의힘으로자석이붙어있는catheter를움직인다

②기존의모든catheter를사용할수있다.

③큰금속이식편을가지고있는환자에게는금기이다.

④천공위험이거의없다.

2. Magnetic navigation 시스템은어느정도의자기장에서구현되는가?

①0.08 Tesla

②0.8 Tesla

③1.5 Tesla

④3.0 Tesla

3. CARTO 시스템에대한설명으로적당하지않은것은?

①Catheter 위치인식을위해자장과전류를이용한혼합방식을이용한다.

②AccuResp라는프로그램을통해호흡에의한움직임을동기화한다.

③Circular mapping catheter를통해fast anatomical mapping을시행할수있다.

④모든catheter를사용할수있다.

4. NavXTM system에대한설명으로적당하지않은것은?

①초기에는non-contact mapping인Ensite ArrayTM가사용되었다.

②Ensite NavXTM는6개의electrode에서8 KHz의전류신호가방출되면서형성된자기장을이용하는시스템이다.

③최근OneModel기법을통해false space를없애고editing time을감소시켜더빠르고정확한mapping이

가능해졌다.

④ Magnet 기반시스템을이용하여catheter 위치를확인한다.

부정맥연구회지에서는 매호 자율 학습 문제를 수록합니다. 해당 호에 실린 원고를 바탕으로 출제된 문제로선생님들의자기계발에도움이되시길바랍니다. 많은참여부탁드립니다. 모범답안은다음호에게재합니다.